In various prior patents, I have shown how certain modifications of collagen, collagen-like compounds and gelatin could augment the hemostatic properties of such compounds by manipulation of the surface charge and microstructure thereof. In U.S. Pat. No. 4,238,480, I disclosed that an improved hemostatic agent could be made by treating collagen or collagen-like substances to render the surface charge effectively more positive and that the thusly modified substance could be employed to control or terminate bleeding.
Other references relate to the provision of liquid absorbent patches, pads or the like to carry medicaments. For example, in U.S. Pat. No. 4,022,203, Ackley discloses a liquid absorbable pad means containing a quantity of blood coagulating substance to reduce blood flow. In U.S. Pat. Nos. 4,390,519 and 4,404,970 I disclosed that a modified blood-soluble hemostatic agent could be combined with or incorporated into a porous or supporting body such as, for example, a gauze pad, a bandage, a laparotomy pad or a sponge. By embodying the improved hemostatic agent into such porous body, the resulting article itself becomes a hemostatic material possessing the properties of the agent and may be applied to an area of trauma or injury where such properties may be utilized.
I have now discovered that there are certain additional advantages which result from the use of a composite medical article if an onlay of a medicinal substance can be fused to the surface of an article which has already been impregnated with the same or a different medicinal substance so that the medicinal onlay is the first to come in contact with an area of trauma or injury.